The '''electron''' is a fundamental subatomic particle that carries an electric charge. It is a spin-½ lepton that participates in electromagnetic interactions, and its mass is less than one thousandth of that of the smallest atom. Its electric charge is defined by convention to be negative, with a value of −1 in atomic units. Together with
atomic nuclei, electrons make up atoms; their interaction with adjacent nuclei is the main cause of chemical bonding.
Within an atom, electrons surround a
nucleus composed of
protons and
neutrons in an
electron configuration
. The variations in
electric field generated by differing numbers of electrons and their configurations in atoms determine the chemical properties of the elements. These fields play a fundamental role in chemical bonds and chemistry.
Electrons in motion produce an electric current and a magnetic field.
The electron is one of a class of subatomic particles called leptons, which are believed to be fundamental particles (that is, they cannot be broken down into smaller constituent parts).
As with all particles, electrons can also act as waves.
The antiparticle of an electron is the '''
positron''', which has the same mass but positive rather than negative charge.
==Properties and behavior==
Electrons have a negative electric charge of −1.6022 × 10
−19 coulombs, a mass of 1 E-31 kg|9.11 × 10
−31 kg based on charge/mass measurements and a relativistic rest mass of about 0.511 MeV/Speed of light|c
2. The mass of the electron is approximately
1/
1836 of the mass of the
proton. The common electron symbol is '''e
−'''. [
http://physics.nist.gov/cgi-bin/cuu/Value?me]
Electrons in an atom are '''bound''' to that atom; electrons moving freely in vacuum, space or certain media are '''free''' electrons that can be focused into an electron beam. When free electrons move, there is a net flow of charge, this flow is called an electric current.
A body has an electric charge when that body has more or fewer electrons than are required to balance the positive charge of the nuclei. When there is an excess of electrons, the object is said to be negatively charged. When there are fewer electrons than
protons, the object is said to be positively charged. When the number of electrons and the number of protons are equal, their charges cancel each other and the object is said to be electrically neutral.
When electrons and
positrons collide, they annihilate each other and produce pairs of high energy
photons or other particles. On the other hand, high-energy photons may transform into an electron and a positron by a process called
pair production, but only in the presence of a nearby charged particle, such as a nucleus.
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Last modified: 17.09.07 by jross
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